Blasting Terms Glossary

Last Updated: 1/11/2018 10:39 a.m.

Blasting can be an important part of construction projects, but it remains a specialty. As with any specialty, the terms and language used during the planning and execution of blasts can be difficult to understand if you’re unfamiliar with them. In the blasting industry, these terms are often vital for the promotion of a safe and effective environment for the storage, transport and use of explosive materials.

We’ve created this blasting terms glossary to better promote the use of safe and clear language throughout the commercial blasting industry.

Below, please find this glossary of blasting terms. Feel free to bookmark it for use as a resource or read through the terms to familiarize yourself with blasting and the language used by professionals in the commercial blasting industry. Also, if you know of commonly-used terms that should be added, feel free to reach out to us directly with the terms so we may keep a comprehensive and up-to-date glossary:

Acceptor: Explosives or other blasting agents that are affected by (i.e. receive an impulse from) a donor charge that explodes.

Air Blast: Any blast delivers a shock wave through the air that begins with the actual explosion.

Air-Overpressure Limits: Also known as “air blast,” air-overpressure is the pulsating pressure changes in the area above and below the explosion. Air-overpressure is limited in units of decibels-L, or dBL.

American Table of Distances: The Institute of Makers of Explosives (IME) creates a quantity-distance table that features guidance for storing explosive materials at safe distances from structures, infrastructure and other explosives.

Ammonium Nitrate: Also known as NH4NO3, which is the ammonium salt of nitric acid.

Ampere: When 1 volt is resisted by 1 ohm, it creates a single unit of electrical current known as an ampere.

ANFO: An amalgamation of ammonium nitrate and fuel oil that is highly explosive.

Artificial Barricade: Earth formed in a wall or mound at a minimum thickness of 3 feet for protection from a blast.

Authority Having Jurisdiction: The location of any blast is regulated by different government agencies, offices and individuals, each of which is an authority having jurisdiction for the approval of procedures, equipment and installations.

Available Energy: Explosions and explosive materials create energy, but not all of it is useful for actual blasting. The useful energy is specifically known as available energy.

Barrier: Any object or collection of objects that separates in an unmistakable manner an area for blasting. For examples, warning tape and signs, cones, etc.

Base Charge: The primary charge for explosion at the detonator’s base.

Blast Area: The full area that can experience any flying rock, debris or gas during and after a blast.

Blast Mat: Mats often made of steel cable that reduce risk by preventing debris and flyrock from posing danger to bystanders and blasting crew members.

Blast Pattern: The array of locations for blast holes and/or the relationship between burden and spacing distance.

Blast Site: The complete area where personnel handles explosive materials prior to detonation.

Blast Walls: Protective barriers that can be used to shield people and sensitive structures such as airports, boiler rooms, chemical facilities and other buildings that pose a high-degree or explosive risk.

Blaster: The individual who is fully responsible for loading and firing a blast.

Blasting Accessories: Effective blasts require the use of non-explosive materials known as blasting accessories.

Blasting Agent: An explosive material that meets official standards for insensitivity and that is regulated in how it can be stored and transported.

Blasting Cap: A detonator that is triggered by a safety fuse.

Blasting Crew: The team of people who facilitate a blast from start to finish, including loading, tying in and firing.

Blasting Galvanometer: A resistance instrument powered by electricity that is used in testing electric detonators and circuits.

Blasting Log: Oftentimes a law or regulation will require a written record that includes specific details about a blast.

Blasting Machine: Used in an electric blasting circuit, a blasting machine delivers the current that energizes a detonator

Blasting Support Personnel: Blasting requires a series of independent consultants who specialize in different aspects of blasting, including vibration monitoring, pre-construction surveying, blast planning, etc.

Blasting Vibrations: The post-blast energy that travels through the earth away from the blast area.

Blend: A mixture created for blasting, typically ammonium nitrate or ANFO mixed with a water-based explosive material or oxidizer.

Booster: A high-strength explosive charge that is used to enhance the initiation of low-strength explosive materials.

Box: Approved packaging used for storing and transporting explosives, typically made of plastic, plywood, fiberboard or metal.

Bullet-Resistant: A term that indicates the doors or walls of a magazine are resistant to 150-grain M2 ball ammunition fired from a .30-caliber rifle from a distance of 100 feet perpendicular to the door or wall and having a muzzle velocity of 2,700 feet per second.

Bullet-Sensitive Explosive Material: Explosive material that may be detonated using a bullet meeting the same standards outlined above in the bullet-resistant section.

Burden: The amount of rock broken and displaced by a blast as measured by the distance between the closest free face and the actual blasting hole.

Bus Wire: Bare copper wire in a heavy gauge that can be used to connect detonators or a series of them.

Cap Crimper: A small device used to crimp the metal shell of a fuse detonator to the safety fuse.

Cap Sensitivity: The degree of sensitivity to initiation that a specific explosive has to its detonator.

Capacitor-Discharge Blasting Machine: A blasting machine that stores energy on a capacitor for distribution through a blasting circuit that features electric detonators.

Cartridge: A closed bag, shell or tube that contains explosive materials.

Cartridge Count: Also known as stick count, the number of cartridges included in a standard case, which can typically accommodate 50 pounds of explosive materials.

Cartridge Punch: A device used to punch a hole or similar opening in a cartridge through which a detonator can be inserted.

Case: A shipping container that meets the Department of Transportation’s guidance for the transport and storage of explosive materials.

Case Insert: Printed instruction and warnings that are placed inside any case of explosive materials.

Case Liner: A barrier inside a case that’s designed to prevent the escape of any explosive materials inside.

Certified Blaster: An individual certified by a regulatory individual or body who handles the preparation, supervision and execution of a blast.

Charge per Delay: The totality of charts weights firing during any given span of 8 milliseconds.

Circuit: A path through which electrical current can travel.

Class A Explosives: As defined by the Department of Transportation, explosive materials that can create maximum hazard. The list of Class A Explosives includes dynamite, nitroglycerin and similar materials.

Class B Explosives: As defined by the Department of Transportation, explosive materials that can create a flammable hazard. This list of Class B Explosives includes flash powders, propellant explosives and similar materials.

Class C Explosives: As defined by the Department of Transportation, explosive materials that include Class A or B explosives, but that use Class A or B explosives in restricted amounts.

Code of Federal Regulations: A codification of the general and permanent rules published in the Federal Register by the Executive departments and agencies of the Federal Government. The code is divided into 50 titles which represent broad areas subject to Federal regulation.

Commercial Explosives: Explosives materials that are meant for commercial uses rather than military uses.

Connecting Wire: The wire used in an electric blasting circuit to extend the legwires or firing line.

Continuity Check: An evaluation that should conclude an initiation system has no improper connections or breaks that could lead to failure or a pause of the initiation process.

Core Load: Expressed in grains or explosive per foot, the explosive core included in a detonating cord.

Crimping: Compressing a fuse cap’s shell against a safety fuse.

Current Leakage: The unintended bypass of a portion of the firing current around the blasting circuit.

Current-Limiting Device: A device that is used to limit current amplitude, current flow duration or total energy delivered to the blasting circuit.

Cushion: Also known as trim blasting, cushion is a technique for controlled blasting that includes detonating a blast hole line along the rock face during the blast’s last delay period.

Cutoff: A break in the initiation or detonation path as caused by shifting ground, flyrock or other interference.

Date-Shift Code: A code that manufacturers include on the exterior of shipping containers to assist in the identification and tracking of explosive materials.

Decibel: A unit typically used to measure the air overpressure of an air blast.

Deck Loading: Also known as decking, this loading technique includes placing two or more charges into the same hole, separating them using an air cushion or stemming.

Deflagration: Any explosive reaction that travels through an explosive material at less than the speed of sound.

Delay: A pre-planned and distinct pause between detonations or initiations to allow for explosive to fire separately.

Detonating Cord: A cord that contains explosives and that is used to initiate other explosives.

Detonating Primer: A device assembled as a unit that includes both a detonator and an extra charge of explosives.

Detonation: The explosive reaction that moves through explosive materials at a speed greater than the speed of sound.

Detonation Pressure: A detonating explosive’s pressure produced.

Detonation Velocity: The speed at which a detonation moves through an explosive material.

Detonator: A device used for initiating a detonation.

Donor: An explosive that creates an impulse that then affects an acceptor charge.

Do's and Don'ts: A portion of the instructions inserted into cases of explosive materials that outline guidance for handling, storing and transporting those explosives.

Electric Blasting Circuit: A circuit that also includes detonators and their associated wiring.

Electric Detonator: A detonator that uses electric current as its means for initiation.

Emulsion: Explosive material that is characterized by significant amounts of oxidizers dissolved in water and surrounded by a fuel.

Explode: The actual chemical reaction that produces heat and pressure.

Explosion: The rapid expansion of gases that takes place during a chemical reaction.

Explosive: A device, mixture or compound that is meant to create an explosion.

Explosive Materials: A category inclusive of explosives as well as detonators and blasting agents. Explosive materials are classified as Class A, B or C.

Explosive Strength: The measure of energy released by an explosive at detonation.

Fertilizer-Grade Ammonium Nitrate: A specific type of ammonium nitrate as classified by The Fertilizer Institute.

Fire Extinguisher Rating: A rating given to fire extinguishers that indicates an extinguisher’s relative effectiveness.

Fire-Resistant: A material or structure constructed to protect against damage from fire.

Firing Current: Electric current that is sufficient to energize an electric detonator or a circuit.

Firing Line: The wire connecting a blasting circuit to a power source.

Flammability: The degree to which it is easy to ignite an explosive material using heat or flame.

Flash Point: The lowest possible temperature at which vapors from a combustible substance ignite when exposed to a flame.

Flyrock: The rocks propelled by an explosion’s force in the blast area.

Free Face: Rock surfaces adjacent to water or air that allow for expansion at the time of fragmentation.

Fuel: Any substance that produces combustion after reaction with oxygen.

Fumes: The gases that emerge immediately following an explosion.

Fuse Cap: The detonator initiated by a safety fuse.

Gap Sensitivity: The maximum distance between a donor and acceptor that will allow for propagation.

Ground Fault: The electrical contact between earth and blasting circuit.

Ground Vibration: The shaking of the ground as caused by the shock waves emanating from a blast.

Hangfire: When a blast detonates at some point following its intended firing time.

Hanging Wall: When blasting on an inclined vein, any wall or rock on the vein’s upper side.

Heading: When creating development or exploration passageways, the heading is the driving of openings in those passageways.

High Explosives: Explosives that are specifically known for their high rate of development and reaction, as well as for the explosive’s detonation wave.

IME-22 Containers and Compartments: The Department of Transportation allows for the transport and storage of certain types of explosives and detonators on the same vehicle, as long as the transport and storage follow IME SLP-22 specifications. Compartments are fixed to vehicles, while containers are portable.

Incendivity: An igniting agent’s property that allows the agent to create ignition.

Inhabited Building: Any structure that people use as a habitation or place of assembly and that is in any way related to the storage, use, transportation or manufacture of explosives.

Initiation: Causing the detonation of an explosive material.

Initiator: The cord or detonator by which an explosive material's detonation is started.

Inner Packaging: Some outer packaging also requires an inner packaging for safety during transport.

Instantaneous Detonator: When a detonator’s firing time is 0 seconds (or close to it within milliseconds) rather than timed or delayed in any way.

Institute of Makers of Explosives (IME): The non-profit body that promotes the safe use and trade of commercial explosives in North America, including but not limited to the use, handling, manufacturing, transportation and storage of explosive materials.

Inventory: A complete accounting of all explosive materials stored in a certain magazine.

Lead Lines or Wires: Wires used to connect a circuit of electric detonators with the power source.

Leakage Resistance: Resistance between the ground and the blasting circuit.

Legwires: A duplex sire (or two single wires) the extend from an electric detonator.

Liquid Fuels: Fuels existing in a liquid state, often used in tandem with oxidizers to create explosives.

Loading: When an explosive material is placed again a surface to be blasted or inside of a blast hole.

Low Explosives: Any explosive materials known for development of a low pressure and/or a low reaction rate.

Magazine: Containers, buildings and structures approved for storage of explosives, with the exception of actual explosive manufacturing structures.

Magazine Keeper: The individual responsible for safely storing and creating an inventory of explosive materials in a magazine, as well as maintenance of spaces where the explosives are kept.

Main Explosive Charge: Explosives responsible for the bulk of the blasting effort.

Manufacturing Codes: Important codes that note the date of manufacture and other information on the package of explosive materials.

Mass Detonate: When explosive material causes the simultaneous detonation or explosion of 90 percent or more of any other material.

Maximum Recommended Firing Current: The highest electric current that can be used while maintaining the safety and effectiveness of an electric detonator.

Mine Safety and Health Administration (MSHA): The agency within the U.S. Department of Labor that enforces safety and health regulations in mining.

Miniaturized Detonating Cord: Any detonating cord whose load is less than or equal to five grains of explosive per foot.

Minimum Recommended Firing Current: The lowest electric current that can be used while maintaining the safety and effectiveness of an electric detonator.

Minimum Gap Sensitivity: The air gap that determines whether or not an explosive material fits gap sensitivity tolerances, as measured in inches.

Misfire: When attempts at initiation result in anything less than full detonation.

Natural Barricade: Hills, timber, ground and other natural features that are sufficient for protection and that from a blast.

Nonelectric Detonator: Detonators that operate independent of electric energy and safety fuses.

Nonsparking Metal: Metal that cannot create a spark when coming into contact with rocks, tools and other hard surfaces.

Occupational Safety and Health Administration (OSHA): A division within the U.S. Department of Labor that focuses on promoting workplace safety and health, as well as the elimination of occupational hazards.

Oxidizer: Substances like nitrates that stimulate the combustion of organic matter by yielding oxygen to other oxidizing substances.

Particle Velocity: The rate at which vibrations travel through the ground as measured by the time rate of change of the ground vibration’s amplitude.

Peak Particle Velocity: The maximum intensity of ground vibration during a blast.

PETN: A commonly used abbreviation for the explosive officially known as pentaerythritoltetranitrate.

Placards: When vehicles carry hazardous materials, official placards indicate what types of materials are on board.

Plosophoric Materials: Two or more chemical ingredients that are capable of creating a blasting explosive but that are non-hazardous on their own.

Pre-Construction Condition Surveys: The area within 500 feet of the blasting is commonly surveyed with a month of the blasting, including utilities, buildings, improvements and more.

Premature Firing: When an explosive charge’s detonation occurs prior to the intended time.

Presplitting: A technique for controlled blasting that creates a continuous or semi-continuous fracture in the space between blast holes.

Primary Explosive: A highly sensitive explosive material that easily detonates when coming into contact with a heat source of appropriate magnitude, such as flames, spark, etc.

Primer: A unit used to detonate other explosives and that includes both a detonator and a detonating cord.

Propagation: When explosive charges detonate due to an impulse from another nearby or adjacent detonation of explosives.

Quantity-Distance Table: A table that outlines recommended distances for placing explosives of various weights to different locations.

Receptor: Receptor charges (or acceptor charges) are the explosive materials that receive an impulse from other explosive materials, which are known as donor charges.

Resistance: The opposition to electrical current’s flow as measured in ohms.

Safety Standard: Recommended safety precautions for use when manufacturing, handling, storing or transporting explosive materials.

Scaled Distance: The relative vibration energy as measured by the distance between a charge per delay and a structure.

Seismograph: An instrument used to record ground vibrations.

Sensitivity: An explosive material’s ability to initiate when receiving an impact, shock, friction, flame or other influences.

Separation Distances: The recommended minimum distances between certain locations and explosive materials.

Sequential Blasting Machine: Also known as a sequential timer, a device meant to initiate different series of detonators at intervals that are accurately timed.

Series Blasting Circuit: When a blasting circuit creates a single continuous path for current to travel through all caps in a single circuit.

Shelf Life: When explosive material is stored, the shelf life is the span of time during which the material maintains its known performance characteristics.

Shock Wave: The transient pressure pulse that moves at a supersonic velocity.

Shot Firer: Also known as a blaster, the individual who holds responsibility for loading and firing a blast.

Silver Chloride Cell: Used in a blasting galvanometer, a silver chloride cell is a unique battery that delivers a relatively low current.

Spacing: The distance spanning blast holes lined up in a row.

Specific Gravity: A ratio that expresses the weight of pure water to the weight of an equal volume of another substance.

Stability: An explosive material’s ability to retain is physical and chemical properties when exposed to different environmental conditions over different periods of time.

Static Electricity: The electric charge that is at rest on an object or person.

Stemming: A technique used for limited air-overpressure and rock movement that involves drilling a blast hole beyond or below the desired excavation limit or depth.

Storage: Using specially designed spaces to safely keep explosive materials between manufacturing and use.

Stray Current: When an electric current flows outside of an insulated conductor system.

Subdrilling: The drilling of a blast hole or a portion of a blast hole below or beyond the planned excavation depth or limit.

Sympathetic Propagation: When an explosive material’s detonation results from the impulse of another detonation traveling through water, earth or air.

Temporary Storage: Any space where explosive materials are safely kept for 24 hours or fewer.

Test Blasts: At least two test blasts must be executed on a limited scale before larger-scale blast plans can be submitted for approval.

Theft-Resistant: Measures taken during construction meant to prevent or deter th_e illegal entry of an storage space where explosive materials are kept.

Trunkline: The line of detonating cord that connect to detonating cord downlines and that lies along the ground surface.

Tunnel: Any underground passage that is horizontal (or nearly horizontal) and that remains open at both ends.

Unbarricaded: When explosive storage spaces lack any artificial or natural barricade.

Unconfined Detonation Velocity: When a charge is fired in open space, the rate of detonation during that unconfined explosion.

Vibration Limits: Blasting causes vibration in surrounding structures, and this vibration is limited (in inches per second) depending on the types of buildings in the immediate vicinity (residential, commercial, public, historic, etc.)

Volt: The different in the potential needed to force a 1 amp current through 1 ohm resistance, which is electromotive force.

Warning Signal: Any signal given visually or audibly that warns personnel and bystanders in a blast area’s vicinity of the impending explosion.

Watt: A measurement of electrical power that equals 1 joule per second.

At TM International, LLC, we support commercial blasting through a series of products that help making blasting safer and more effective, including our commercial blasting mats and similar materials. If you need control for commercial blasts or other commercial blasting equipment, get in touch with us about our line of products.

Also, this glossary is meant to be a helpful resource for those working in and around the commercial blasting industry. If you know of terms that should be added, please feel free to let us know. And certainly feel free to pass this resource along to anyone in the commercial blasting industry whom it might help.

Contact us today with questions or interest in commercial blasting mats and other products that deliver control for commercial blasts.

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